An electronic endoscope system is used for observation and treatment inside a human body. When endoscopic observation is performed using an electronic endoscope system, it is necessary to accurately identify lesion sites and normal sites. A lesion site often has a different color tone from a normal site due to angiogenesis or the like. Patent Document 1 discloses an electronic endoscope system that includes a function for assisting endoscopic image diagnosis by specifying a site that has a high likelihood of being a lesion site based on color information in an endoscopic image, and displaying the specified site in an emphasized manner.
In order to accurately specify a lesion site or the like based on color information in an endoscopic image as described above, it is necessary to acquire an endoscopic image that has accurate color information at least in the color region used when specifying the lesion site or the like. Conventional electronic endoscope systems include a white balance correction function as a function for correcting color information in an endoscopic image.